Abstract

West Indian manatees (Trichechus manatus) are found in the southeastern United States, the Caribbean, and from eastern Mexico along the north coast of South America to eastern Brazil. Florida manatees (Trichechus manatus latirostris) have been documented along the Western North Atlantic, but are thermally restricted in winter to the Southeastern U.S.

In the summer of 1994 the Maryland Department of Natural Resources received reports of a live manatee in the Upper Chesapeake Bay. By October 1, the animal known later as "Chessie" was captured and successfully returned to Florida. In 1995, Chessie traveled from Florida to as far as Rhode Island which was the first time a Mid-Atlantic region manatee's travels were documented using satellite and radio transmitters. Summertime sightings of live manatees in Maryland have been increasing in the last decade.

While anecdotal reports of manatee carcasses are present in Maryland records of only three dead manatees have been documented in the state. (1) In April 2010 a manatee carcass was reported on the banks of the Patuxent River. The partial carcass likely died the previous fall and surfaced on the first warm days of spring. (2) On October 27, 2015, a manatee carcass was observed at Assateague Island National Seashore by the National Park Service (NPS), and the stranding was reported to the Maryland Department of Natural Resources Marine Mammal and Sea Turtle Stranding Program. Due to a severe storm over the next two days, the carcass washed out, but was recovered on October 29 and transported to the Smithsonian Institution for necropsy the following day. Water temperature on the initial day of the stranding was 62°F (3) On November 21, 2016, a manatee carcass was reported by Dundalk Marine Terminal staff, but over the next two days high winds moved the carcass. Water temperatures were decreasing from 58°F to 52°F throughout the week preceding the initial report. It was eventually located, collected, and a necropsy examination was conducted. Prolonged exposure to temperatures below 68°F cause can cause cold shock and cold stress syndrome which may lead to death (Bossart et al. 2002).

Acknowledgments

The authors wish to thank the National Aquarium for assistance with live manatee sightings; the National Park Service/Assateague Island National Seashore, Dundalk Marine Terminal, Calvert Marine Museum, the Smithsonian Institution /Osteo-Prep Lab for assisting with manatee carcass recovery, and the USGS National Wildlife Health Center for conducting diagnostic tests. Without the help of all collaborators our efforts in documenting extralimital manatees would not be possible.

* Presenting author

Literature Cited

1.  Bossart, GD, Meisner RA, Rommel SA, Ghim S, Jenson B. 2002. Pathological features of the Florida manatee cold stress syndrome. Aquatic Mammals. 29;1:9–17.